1. Field of the Invention
The present invention relates to a method of rolling plates from input stock in several successively arranged work steps, wherein, depending on the desired end product, different numbers of n passes are carried out in one or more roll stands, preferably in a hot-rolling reversing stand.
2. Description of the Related Art
When rolling plates from an input stock in a plate rolling stand, preferably in a hot-rolling reversing stand, the development tendencies are to roll strips which are as long as possible for reasons of maximizing productivity and yield (minimizing crop losses at the sides and ends). As a result of the process operation carried out usually for this purpose, hot reversing rolling with relatively small end thicknesses leads to very large rolling force differences between the strip beginning and the strip end, particularly in the last passes, wherein the differences may be, for example, up to 25,000 kN. The reason for this is the lower temperature of the rolling stock at the strip end caused by cooling taking place during rolling which requires the rolling work or rolling force to increase.
In order to counteract the effects of the cooling taking place during rolling in passes carried out successively, Patent Application WO-A-89/11363 proposes to heat the rolling stock up again at least after the first deformation step, preferably by means of an induction heating unit, and only then to carry out the second deformation step. However, this method is very expensive because it is necessary to install an appropriate furnace for this purpose and additional electrical energy must be used. In addition, it is very difficult to use this method in the case of reversing rolling.